The aim of this research proposal is to examine the difficulty that older listeners who wear hearing aids have with speech recognition, with a focus on wide-dynamic range compression (WDRC) processing. To accomplish this, two areas will be examined: the effects of aging on temporal resolution and the effects of varying compression ratio on speech recognition in older listeners. WDRC amplification alters the temporal complexity of a signal. The effect of this processing on the speech recognition ability of older listeners with existing temporal processing deficits is still unknown. The situation is further complicated when the task involves recognition of speech, itself a temporally complex signal, in a background of temporally complex noise. The specific aims of this project include determination of how older hearing-impaired listeners are affected by amplitude modulation in background noise when listening to speech in noise processed by WDRC amplification. Older and younger hearing-impaired and normal- hearing listeners will be tested. Experimental tasks will include a speech recognition test in which speech is presented in three background noises of increasing temporal complexity. The speech and noise combinations will be processed by amplitude compression at three compression ratios. In addition, to determine if older listeners' performance with WDRC amplification is related to any underlying temporal resolution deficits, a modulation detection and a temporal- order judgment task will be completed. In addition to defining the auditory capacities and limitations of older listeners, these results will help to provide older listeners with optimal amplification.